Neogene grassland expansion and climatic evolution

Evapotranspiration is one of the most significant inputs in the terrestrial hydrologic budget. ET rates, however, vary greatly between vegetation types. Paleoenvironmental changes, such as the rise of grass-dominated ecosystems during the Neogene, would dramatically affect vapor recycling and ultimately drive changes in the hydrologic regime. We are applying several techniques to examining the relationship between changes in vegetation cover and concurrent climate change: 1) Stable isotopic paleoclimate records from sedimentary basins around the world. 2) Simple moisture transport models to assess the isotopic effects of changing vegetation. 3) Isotope-tracking general circulation modeling to improve our understanding of these interactions between the biosphere and the climate system. See our most recent papers in Earth and Planetary Science Letters (Mix et al., 2013) and Global Biogeochemical Cycles (Chamberlain et al., 2014).